Chapter 4: Optical systems & ray tracing
4.0 Introduction
This chapter is a practical introduction to geometric optics, ray tracing, and optical system design in OghmaNano. It is written for physicists, engineers, and researchers who want to understand how light propagates through real optical systems — lenses, apertures, mirrors, detectors, and multi-element assemblies — using explicit ray optics rather than black-box optimisation.
The approach is deliberately geometric and visual: rays are traced in full 3D, you inspect where they go, identify which surfaces do the work, and diagnose behaviour such as vignetting, clipping, and wavelength-dependent throughput from detector images and spectral plots. The aim is to build a reliable workflow: start simple, inspect rays, then increase realism and complexity.
The pages below form a connected cluster. If you are new to the Optical Workbench, start with the overview, then move on to detectors, and finally work through a complete lens system as a worked example.
4.1 Overview: Optical systems & ray tracing
Start here for the overall workflow and the main Optical Workbench concepts: sources, optical elements, ray propagation, and inspecting ray paths in 3D.
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Optical systems & ray tracing
Overview of the Optical Workbench workflow and ray-tracing outputs. -
S-plane editor
Surface-by-surface lens editing (radii, thickness, materials) with full 3D ray tracing.
4.2 Detectors and recorded images
Detectors convert ray hits into spatial intensity distributions. This is where you connect ray geometry to measurable outputs: images, spot patterns, and throughput.
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Optical detectors
Detector planes, recorded intensity maps, and wavelength-dependent collection efficiency.
4.3 Worked example: Cooke Triplet lens
The Cooke Triplet is a historically important three-element lens and a good first complete system to study. The tutorial uses detector images and efficiency spectra to build intuition about losses, clipping, and spectral throughput.
- Cooke Triplet (Part A): Optical response
- Cooke Triplet (Part B): Analysing performance
- Cooke Triplet (Part C): Modifying and improving the design
Recommended path through this chapter
- Read the overview and run a first ray trace.
- Learn how detectors record images and efficiency spectra.
- Work through the Cooke Triplet tutorial (A–C) as a complete worked example.
- Use a dense wavelength mesh (e.g. 200–1500 nm, 20 points) whenever you want smooth spectral plots.
Common pitfalls
- RGB sampling is fine for images but produces jagged/meaningless spectra.
- If your efficiency curve is ~100% everywhere, your detector may be placed before the optics.
- If your image is blank, check that the detector is behind the lens group and the source points towards it.